NAME
Digest::HMAC - Keyed-Hashing for Message Authentication
SYNOPSIS
# Functional style
$digest
= hmac(
$data
,
$key
, \
&myhash
);
hmac_hex(
$data
,
$key
, \
&myhash
);
# OO style
use
Digest::HMAC;
$hmac
= Digest::HMAC->new(
$key
,
"Digest::MyHash"
);
$hmac
->add(
$data
);
$hmac
->addfile(
*FILE
);
$digest
=
$hmac
->digest;
$digest
=
$hmac
->hexdigest;
$digest
=
$hmac
->b64digest;
DESCRIPTION
HMAC is used for message integrity checks between two parties that share a secret key, and works in combination with some other Digest algorithm, usually MD5 or SHA-1. The HMAC mechanism is described in RFC 2104.
HMAC follow the common Digest::
interface, but the constructor takes the secret key and the name of some other simple Digest::
as argument.
The hmac() and hmac_hex() functions and the Digest::HMAC->new() constructor takes an optional $blocksize argument as well. The HMAC algorithm assumes the digester to hash by iterating a basic compression function on blocks of data and the $blocksize should match the byte-length of such blocks.
The default $blocksize is 64 which is suitable for the MD5 and SHA-1 digest functions. For stronger algorithms the blocksize probably needs to be increased.
SEE ALSO
Digest::HMAC_MD5, Digest::HMAC_SHA1
RFC 2104
MAINTAINER
Andrew Rodland <arodland@cpan.org>
ORIGINAL AUTHORS
Graham Barr <gbarr@ti.com>, Gisle Aas <gisle@aas.no>